The preparation of nitrodiphenylamines by reaction of corresponding aromatic amines with p-nitrochlorobenzene in the presence of an acid acceptor or a neutralizing agent, optionally in the presence of a catalyst, is known and is described, for example, in DE-A 3,246,151.
The disadvantages of the processes described above are often the inadequate selectivities which, in addition to losses in yield, as a rule, necessitate more or less expensive purification steps before the nitrodiphenylamines can be reacted further, for example by hydrogenation to 4-aminodiphenylamines.
A more recent method for the preparation of arylamines by reaction of amines with aromatic compounds, for example, also halogenated nitrobenzenes, in the presence of a palladium catalyst and a base is described in U.S. Pat. No. 5,576,460. It is furthermore known from EP-A 846,676, for example, to react nitrohalogenobenzenes with aromatic amines in the presence of a palladium catalyst, a base and a halide as a co-catalyst.
WO 99/01418 describes the reaction in water with palladium catalysts and water-soluble phosphines. As a rule, the low yields of 20-50% are a disadvantage in this process.